Attempt to copy the cell style between HSSF and XSSF
Added more hash map usage to avoid duplicating cell styles but it still refuses to work
Fixed cloneCellStyle method, works fine now, however note that it is significantly slower than cloning cells between workbooks of the same type.  Test to see if it was not replicating the cell style the long way for HSSF to HSSF was negative, so I am confident it is working the way I intended.
Merge branch 'crossTypeStyleCopy'